The present invention relates to a motor vehicle in which the body at least in parts is not produced in a conventional way from sheets of metal or self-supporting metal sheet body.
Many parts or regions of the body as well as complete bodies are recently produced of synthetic plastic orframe constructions are provided with a covering of synthetic plastic. Synthetic plastics are also utilized as materials for motor vehicle window panes with corresponding finishing, surface treatment and coating.
Depending on the degree of the substitution of the conventional materials, completely new conditions and operations for the selection and design of antennas for reception and transmission operation and for their arrangement in the vehicle are provided. In addition, the number of the antennas for different objectives which must be installed on the vehicle increases. As a result, not a few new antennas with different frequency regions and radiation characteristics are integrated in the modern vehicle, in addition to the known systems.
The new premises for the antenna configuration result first of all from a changed influence of the electromagnetic fields, within which the vehicle is located or moves. The vehicle body has been formed as a parallelepiped of sheet metal. A part of the roof surface generally rests on bar-like elements or cross beams, while great, substantially rectangular openings or windows are located between them and closed with a dielectric material or glass pane. This construction is located closely over the great mass of the ground surface and is surrounded by an electromagnetic field caused from a plurality of sources, hereinbelow referred to as transmitters, whose signals must be received. Moreover, the vehicle can carry a transmitting radiator.
The metal part of the body and the dielectric of the panes leads to a characteristic deformation of the surrounding field and to different field concentrations around the vehicle and in the region of the window openings. From this field presently signals are uncoupled first of all with rod antennas and radiation structures in the window panes.
The metal body supports on the one hand the operation of the antennas as a wave type convertors and couple elements within predetermined regions, and on the other hand, supplies the metal surfaces of the required ground potential for the antennas.
When individual or all sheet metal surfaces of the vehicle are replaced by those composed of synthetic plastic, then the field formation and field concentration around the vehicle changes, and the ground potential, as the vehicle can be taken into consideration, fails or changes dramatically. As a result, the conditions for selection and arrangement of the antennas change or the predetermined configurations can not be used at all or can be used only conditionally.
Also, the introduction of window panes of synthetic plastic and of synthetic plastic/glass combination causes changes as well. With the new pane structure, metal-ceramic conductor tracks are applied with high temperature processes not in the same way as with conventional glass panes. Also, a use of such conductor tracks and substantially of inserted thin wires for heating purposes is questionable due to the required temperatures of the heating operation.
For the pane heating a following solution is provided:
The synthetic plastic pane is provided with a flat, electrically conductive metal coating which is connected to the direct current power supply. With a suitable arrangement of the heating current terminals, a uniform heating of the pane surface is provided without a high surface temperatures.
A window pane with a substantially closed metal coating and good electrical conductivity is however not suitable for the arrangement of wire and conductor track structure in the known manner and for its use as antenna radiator.
The problem of arranging of antennas relative to the body parts of synthetic plastic was addressed at an initial stage of the modern development in German patent application no. 195 35 250. The research which was conducted in connection with this application provided a series of patents which can give a good overview of the research and possibilities in this area. The proposed solutions were used for a transition from a conventional construction of the body and the design in steel sheets which is basically maintained. Only individual parts of the body were composed of non-metallic materials, and the antennas were applied on these parts. The antennas are arranged for example in and under the roof shells of synthetic plastic material, in a folding roof or a hard top of a cabriolet, in passenger space or motor hood and in shock absorbers.
These solutions, however on the one hand, are connected with the availability of the sheet metal body of the body of the vehicle and when the ground potential and the influence of the surrounding field is utilized. On the other hand, these factors act in disturbing manner for predetermined possible antennas and frequency regions.